Role of neglected parasitic diseases in the era of COVID-19 pandemics.

There are some doubts about the exact relationship between neglected infectious diseases (NIDs) and COVID-19 disease, which remains to be clearly defined. The present review summarized the effect of parasitic infections as the risk factors or protective agents in the COVID-19 pandemic. Parasites could proficiently modulate immune responses. Thus, parasitic infections could have a different impact on the incidence and clinical severity of COVID-19 in different regions of the world. Also, restoring programs to prevent, treat, and control NIDs, in particular helminths, could help in reducing the incidence and mortality of COVID-19 in endemic areas and help to increase vaccination effectiveness. Changes in the gut microbiome associated with helminth infection may have systemic immunomodulatory effects toward suppressing host immune responses, reducing vaccine efficacy and increasing the severity of other infectious diseases. The cytokine storm observed in severe cases of COVID-19 is characterized by a predominance of proinflammatory cytokines, such as IL-6. However, it is possible that helminth infection could change the outcome of infection by modifying the Th2 response to limit the inflammatory component; this would be particularly apparent in areas endemic for helminthic infections, which suggests a possible protective effect against COVID-19. Because parasitic infections affect more than 2 billion people throughout the world, their impact on COVID-19-associated effects on public health could be considerable. Further studies with larger sample sizes would be needed to explore the possible role of neglected parasitic infections in the COVID-19 pandemic.